IRJET- Review of Cold-Formed Built-Up Compression Members

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 06 Issue: 04 | Apr 2019 www.irjet.net p-ISSN: 2395-0072
© 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 4248
Review of Cold-formed Built-up compression members
A.PRIYANKA1, G.ARUNA2
1 PG Student, Structural Engineering, Sona College of Technology, Salem
2Associate Professor, Civil Department, Sona College of Technology, Salem
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Abstract: The purpose of this paper is to understand the
strength and behaviour of cold-formed steel built-up
section under compression. Combination of two individual
sections connected by various fastening sections were
called built-up sections. The review of experimental,
numerical and theoretical investigations on built-up
sections were presented. Comparison were made for
design strength calculation for various code books. The
recommendation of authors for designing the built-up
sections were presented.
KEYWORDS: Cold-formed steel, built-up section, column,
experimental investigation, numerical analysis.
1. INTRODUCTION
In industrial growth of construction, the utilization of cold-
formed steel were becoming more applicable. Back-to-
back built-up cold-formed steel channel sections were
widely utilized as compression members in structures.
(Tina Chui Huon Ting, Krishanu Ro 2017). The local
buckling resistance of built-up members does not get
improved by the overlapping of ﬂanges. Anyway, it does
enhance the distortional buckling resistance to some
extent. (M. Adil Dar et al (2018).
Cold-formed steel (CFS) structures were widely utilized
compared to hot-rolled steel structures and there were
research on more structurally efficient cross-sectional
shapes. It was found that for column members in cold-
formed steel structures face-to-face built-up cold-formed
steel channel sections were becoming increasingly
popular. Usually the hot-rolled sections always fail as a
result of global buckling, but the cold-formed sections may
fail in distortional or local buckling (Biggs 2008).
2. REVIEW OF BUILT-UP SECTION
Krisda Piyawat and Chris Ramseyer (2013) carried out
investigation on the development of an Axial Load
Capacity Equation for Doubly Symmetric Built-Up Cold-
Formed Sections. In this paper 360 different
configurations were carried and the numerical result were
compared with the specifications from American Iron and
Steel Institute. Out-of-straightness and out-of-flatness,
were thoroughly investigated and the axial load capacities
and failure modes were analysed. A regression analysis of
a three-dimensional surface fitting and calibration with
the experimental data were carried out. It was found that
2007 AISI specifications were overly conservative for
double symmetric built-up sections after analysing it with
numerical analysis. A simple and reliable axial load
capacity equation was then developed. By ensuring safety
and efficiency, as well as numerically simulated and
experimentally measured capacities an equation is
proposed which was in good agreement. A distortional
buckling mode occurs for a short member and 0.88 was
the average of the experimental to numerical strength
ratios.
Mohamed Dabaon, Ehab Ellobody (2014) carried out
investigation on nonlinear behaviour and design of built-
up cold-formed steel section battened columns. The built-
up columns were designed with pin-ended boundary
conditions and consisted of two cold-formed steel
channels placed back-to-back and were connected using
batten plates. The nonlinear material properties of flat
and corner portions of the channels, initial geometric
imperfections, actual geometries as well as the boundary
conditions were carefully considered in the models.
Fig-1: Test setup for the built-up cold-formed steel section
battened column.
The specifications were unconservative for the built-up
cold-formed steel section battened columns failing mainly
by local buckling, whereas it was found that the
specifications were conservative for the built-up columns
failing mainly by elastic flexural buckling.

David C. Fratamico et al (2017) presented experimental
investigation on the global buckling and collapse of built-
up cold-formed steel columns 16 different CFS lipped
channel sizes connected at the web using a pair of self-
drilling screw fasteners for a column length of 6ft (1.83
m). It was observed that a concentric compression,
displacement-controlled monotonic tests on 32 specimens
were carried out at key locations. Prevalent mode of
failure was local-global interaction. It was observed that
the stud-to-track end condition was determined to be
semi-rigid, but generally closer to a fixed condition.
Southwell approach was utilized for end rigidities. There
was a proposal and validation of test data on rational
design approaches extending the application of the Direct
Strength Method (DSM) and employing current state-of-
the-art numerical modeling techniques. There was a study
undergone for the development of definitive design
recommendations that help reduce the complexity of
fastener designs and incorporates the DSM framework
when predicting built-up member strength. Work was
undergone for bare, unbraced, and unperforated back-to-
back lipped channel sections and were tested using
realistic end conditions by installing each stud in track to
study the buckling behavior and strength of multiple cross
section sizes and varying web fastener layouts. When
more isolated global (flexural) buckling occurs composite
action was developed through the web screws
Krishanu Roy and Tina Chui Huon Ting (2018) conducted
investigation on nonlinear behaviour of back-to-back
gapped built-up cold-formed steel channel sections under
compression. In this literature, nondimensional
slenderness ranges from 1.08 to 1.16. The experimental
results were compared with the numerical non-linear
finite element model and it was found to be in good
agreement with the experimental analysis. After analysing
84 models it was observed that design of section using
American Iron and Steel Institute (AISI) and Australian
and New zealand Standards were conservative by 53%. It
was concluded that slight modification in non-dimensional
slenderness resulted in a gap, and there was a
conservation of 5% in the design standards with respect to
the experimental and finite element results.
Fig-2: Back-to-back built-up cold-formed steel channel
columns without and with the gap in between.
To overcome this problem nonlinear finite-element
analyses were conducted on a total of 360 cases with 18
built-up configurations and compared with the AISI
specification and previous experimental data. For further
validation it was found that the more pure compression
tests on other practical, built-up configurations were
needed for the proposed equation.
Tina Chui Huon Ting et al (2017) carried out investigation
on the effect of screw spacing on behavior of axially loaded
back-to-back cold-formed steel built-up channel sections.
By referring the Australian and New Zealand Standards for
built-up sections a modified slenderness approach was
carried out. For the 300, 500, 1000, and 2000 mm section
lengths, the maximum imperfections of the test specimens
were 0.2, 0.2,0.4, and 0.6 mm. Nearly 30 experimental
tests were conducted for stub to slender columns. Using
ABAQUS 6.14-2 (ABAQUS, 2014) a non-linear elasto-
plastic finite element model and the center line
dimensions were utilized for the cross section design.
Fig-3: Initial imperfection contour for (BU75-S50-L300-1)
Nearly 144 models were utilized by varying the
parametric study and it was found that around 10% stub
columns were unconservative while generally they were
conservative for varying the slenderness approach.
Krishanu Roy, Tina Chui Huon Ting and Hieng Ho Lau
(2018) were conducting investigation on Nonlinear
behavior of axially loaded back-to-back built-up cold-
formed steel un-lipped channel sections. Cold-formed steel
built-up un-lipped channel sections were used as trusses,
wall frames and portal frames. In built up columns,
intermediate fasteners resist the buckling of individual
channel sections. The authors specially investigated the
effect of screw spacing on axial strength of such columns.
Analysing of 95 specimen by finite element, ranging from
stub to slender columns were done. For parametric study
the verified finite element model were utilized for the
investigation on axial strength with the effect of screw

spacing. Presentation on 15% over conservation, were felt
on New Zealand and Australian standards and it failed by
overall buckling. Then 8% unconservation for built-up
columns using the same specification were found to be
failed by local buckling.
Fig-4: Comparison of experimental and numerical analysis
of Short column (BU75-S100-L500)
There was an increase in axial strength by 31% when
built-up lipped channel sections were utilized than the
built-up un-lipped built-up sections.
Krishanu Roy et al (2018) conducted experimental and
numerical investigation into the behaviour of face-to-face
built-up cold-formed steel channel sections under
compression. Presentation on the results of 36
experimental tests were conducted on face-to face built-up
cold-formed steel channel-sections by covering a wide
range of slenderness from stub to slender columns. The
experimental results and the nonlinear finite element
model were found to be in good agreement with each
other.
Fig-5: Effect of screw spacing on axial strength of face-to-
face built-up cold-formed steel channel sections. (a) Stub
columns (Length = 300 mm)
Modelling of intermediate fasteners, initial imperfections
and material non-linearity were done using the finite
element model. Comparison was made between both
finite element and experimental results against the design
strengths calculated in accordance with the American Iron
and Steel Institute (AISI), Australian and New Zealand
Standards (AS/NZS) and Eurocode (EN 1993-1-3).
Comprising of 90 models finite element model was utilized
for the purpose of the parametric study.
Krishanu Roy et al (2018) carried out investigation on the
Effect of thickness on the behaviour of axially loaded back-
to-back cold-formed steel built-up channel sections both
experimental and numerical investigation. For preventing
the channel-sections from buckling independently,
intermediate fasteners were required at discrete points
along the length. The use of modified slenderness by
taking into account the spacing of the fasteners with the
guidance of the AISI &AS/NZS for such back-to-back built-
up cold-formed steel channel sections. To understand the
effect of column thickness and slenderness’s on axial
capacity only limited research had been done on back-to-
back built-up cold-formed steel columns. The results of 60
experimental tests were presented. By varying thickness,
length and cross section of columns, detailed observations
on different failure modes and column strengths were
made. By including the material non-linearity, geometric
imperfections and explicit modelling of web fasteners a
non-linear finite element model was developed. For 204
models comprehensive parametric study was carried out
on wide range of thickness and slenderness, by
considering the back-to-back built-up columns. For local
buckling of stub and short columns AISI& AS/NZS
standards were unconservative while for overall buckling
of intermediate and slender column it was conservative.
M. Adil Dar et al (2018) carried out investigation on
Behaviour of laced built-up cold-formed steel columns,
both Experimental investigation and numerical validation.
Steps were taken to study the performance of
monotonically increasing axial compression loading in the
evaluation of built-up cold-formed steel (CFS) columns.
Four CFS angle sections connected by single lacing
systems were used for the fabrication of five test
specimens of built-up columns. In the test specimens
height of columns, width-to-thickness ratios and
slenderness ratios of chord and lacing elements were the
varied parametes. The main parameters evaluated were
column strengths, axial load vs. displacement response,
mode of failure, and deformed conﬁgurations. Using a
ﬁnite element software ABAQUS the numerical analysis
were carried out.

Fig-7: Various modes of failures observed.
In built-up laced CFS columns, test results were used to
develop the column strength curves. Using the North
American Standards and European Standards for CFS
sections the results of this study were compared with the
design strength.
M.Ranjith and G. Aruna (2018) carried out investigation
related to study on behavior of cold formed built-up
compression member. The behaviour and design of cold
formed steel built-up closed sections with intermediate
stiffeners on both legs of the angle sections were
predicted. The connections of two sections were made
using self-tapping screws which was made at 20 mm
distance from both ends and the connections were made
at 100mm equal interval zigzag throughout the length of
column.
Fig-6: Cross sectional dimensions of the specimen.
The ultimate load prediction by theoretical analysis as
well as for every specimen length and the model
calculation of nominal axial strength of column was also
described. Using self-tapping screws to form a built up
closed box sections then two of the L-sections were
connected at their lip to flange. The D/t ratio was directly
proportional to the ultimate load carrying capacity of the
specimens and it was found to be increased. Distortional
buckling occurs with larger area initially whereas
distortional buckling was the dominant failure for
intermediate columns.
3. CONCLUSIONS
The load-lateral displacement, load-axial strain
relationships as well as the column strengths, failure
modes, deformed shapes at failure were predicted
numerically and compared it with measured experimental
values. For the built-up cold-formed steel sectioned
battened columns it had been shown that the
specifications were unconservative which was failing
mainly by local buckling, and the specification were
conservative for the built-up columns when they were
failing mainly by elastic flexural buckling. It was observed
that there was 53% more strength than the design
standards when non-dimensional slenderness (λc) was
used to calculate design capacity. There was
unconservation for stub columns, when the AISI and
AS/NZ standards were utilized.
REFERENCES
[1] David C. Fratamico and Shahabeddin Torabian, ”
Experiments on the global buckling and collapse of built-
up cold-formed steel columns”, Journal of Constructional
Steel Research, 2018.
[2] Krisda Piyawat and Chris Ramseyer,” Development of
an Axial Load Capacity Equation for Doubly Symmetric
Built-Up Cold-Formed Sections,” Journal of Structural
Engineering, 2013.
[3] Krishanu Roy et al,” Nonlinear behaviour of axially
loaded back-to-back built-up cold-formed steel un-lipped
channel sections”, Steel and Composite Structures, Vol.28,
No. 2(2018) 233-250.
[4] Krishanu Roy,Chia Mohammadjani,”Experimental and
numerical investigation into the behaviour of face-to-face
built-up cold-formed steel channel sections under
compression”, Thin-Walled Structures 134 (2019) 291–
309.
[5] Krishanu Roy and Tina Chui Huon,” Nonlinear
behaviour of back-to-back gapped built-up cold-formed
steel channel sections under compression,” Journal of
Constructional Steel Research, 2018.

[6] Krishanu Roy and Tina Chui Huon Ting, “Effect of
thickness on the behaviour of axially loaded back-to-back
cold-formed steel built-up channel sections - Experimental
and numerical investigation,” research gate, September
2018.
[7] Mohamed Dabaon, Ehab Ellobody,”Nonlinear
behaviour of built-up cold-formed steel section battened
columns,” Journal of Construction Steel Research, 2015.
[8] M. Adil Dar et al,” Behaviour of laced built-up cold-
formed steel columns: Experimental investigation and
numerical validation,”Thin walled structures 132{2018}
398-409.
[9] M.Ranjith and G. Aruna, “Study on behavior of cold
formed built-up compression member,” International
Journal of Advanced Science and Engineering Research,
Volume: 1, Issue: 1, June 2016.
[10] Tina Chui Huon Ting et al,”Effect of screw spacing on
behavior of axially loaded back-to-back cold-formed steel
built-up channel sections,” Advances in structural
engineering, july 2017.

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